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Chloroform

Chloroform MSDS

Chloroform is a valuable chemical used in chemistry. It's main use is as a solvent but it also has some other uses in some syntheses. It is a clear liquid with a sweet/solvent like odor. It is made by a haloform reaction, using sodium hypochlorite and acetone. Sodium hypochlorite is available in low concentrations as bleach.

3NaOCl + CH3COCH3 ----> CHCl3 + CH3COONa + 2NaOH

Sodium Hypochlorite bleach. 1000ml beaker. 600ml can be used, but be careful.
Acetone Seperatory funnel or eye dropper
  100ml or 500ml graduated cylinder
  10ml graduated cylinder
  Thermometer

Into a 1000ml beaker, pour 500ml of 6.00% Hypochlorite bleach. If you are using 5.25%, use the same ammount. Place this beaker in an ice bath and insert a thermometer. Measure out 10ml of acetone. Add the acetone slowly with an eye dropper or burette. Keep the temperature of the bleach below 30C, but try to keep it above 20C. It is not critical to keep it below 30C, I was just setting a refrence point. It also does not matter if the bleach goes below 20C during the additions, the reaction will just be slower. Once all the acetone is added, keep stirring for around 5 minutes. When the temperature of the bleach drops to 20C, take it out of the ice bath and set it in a cool dark place. Check on it occasionally. Once the mixture is the beaker is clear (not cloudy), and you see an oily liquid on the bottom, it is time to extract your chloroform.

Decant the contents of the beaker out (don't let any of the oily liquid out) until you get between 75 and 100ml water left in the beaker. Put this in your seperatory funnel and wait for the oily blob to settle. Once it has, pour it out. This is your chloroform. It would be wise, but not neccesary to clean your sperator funnel out and place the chloroform back in, then shake it with a little distilled water. If you do not have a seperatory funnel, just suck the chloroform out of the beaker with an eye dropper. With 6.00% you should get around 7mls of chloroform, with 5.25% you should get around 5mls. Read the bottom of the page for info on how to store chloroform.

 

Scaling Up

Since chloroform is so useful, 7mls or even 14mls is not enough. Here I have provided you with some simple ratios to use when scaling up. Also, how to do it. The materials needed are the same as above, but the equipment needed is a bit different. To use the ratios, just multiply the number of gallons you are using by the ammount of acetone to get how much acetone to use. So if you're using 2 gallons of 6.00% bleach, then multiply 2 x 83 = 166mls of acetone.

Equipment:

5 gallon bucket

Ice (A 7lb bag is more than enough)

Stick for stirring. This should be something that wont absorb liquids and is not made of metal. I use a large glass tube. If all else fails, just use a normal stirring stick, it works fine.
Graduated cylinder (the appropriate size)
1000ml beaker
Seperatory funnel. This is required, otherwise you'd be there for a long time trying to seperate all the chloroform with an eye dropper.

 

 

 

 

Bleach/acetone/chloroform ratios:

6.00% - 1 gallon of bleach and 83ml of Acetone. This will theoretically make 90ml of chloroform

5.25% - 1 gallon of bleach and 72.5ml of Acetone. This will theoretically make 75.5ml of chloroform.

You can use as much bleach as you like, but sometimes you can not fit it all into the bucket. 2 gallons of bleach is the maximum ammount that should be put in a bucket. The ice you add will displace alot of water. Once all the bleach is in the bucket, dump in your ice (Buy a 7lb bag at the local gas station, that should be enough). Stir this up a bit with your stirring device to cool it. Measure out the acetone you are going to use in a graduated cylinder. While stirring, add your acetone. If you did it right with the ice, you should be able to add all your acetone in under 10 seconds and the ice will still be ice afterwards. The trick is to get the temperature as low as possible before you add the ice, it will tend to stay there. After all the acetone is added, cover the top up and leave the bucket sit in a dark place. Let all the ice melt, then let it rise to room temperature. Sometimes it will go above room temp. Once it reaches room temperature, leave it there for a couple hours. The solution will eventually turn clear and you should be able to see the bottom of the bucket.

Set up a big funnel on another vessel to hold the leftover reactants. Carefully begin decanting the liquid off until there is around 500mls left in the bucket. Be sure not to loose any chloroform (you should be able to see it). Pour this into a 1000ml beaker. Add 400-500mls of water to the bucket and swirl it around a bit. Then add this to the 1000ml beaker also. Set this in the dark for all the chloroform to settle to the bottom. Once it has all seperate, decant as much of the liquid off as you can, then pour the remaining ammount into a seperatory funnel. Drain the chloroform off once it settles (it will be the heavier layer). You can wash this chloroform with water if you want to, but its not neccesary. Do what I do; store the crude chloroform up until you get around 300mls of it, then distil it all at once.

IMPORTANT INFO: The water in 1 gallon of bleach can dissolve up to 19mls of chloroform (Chloroform has a solubility of 0.8g/100ml water). When calculating yeilds, always factor this in. There is no practical way to get the chloroform in there without a large distilation apparatus or lots of a chemical (such as salt) to dissolve into the water and force the chloroform out.

Using 1.5 gallons of 6.00% bleach, I got 95ml of chloroform. Dissolved in the solution there is about 28.5ml. This gives me 123.5mls of chloroform which gives me a 91.2% yeild. This is by far the best yeild I have gotten regarding chloroform and I used the exact instructions above. Now of course I couldn't get that other 28.5ml out of the solution, but you should always count it when determining yeilds.

Storage

Chloroform should always be stored in an amber or cobalt bottle. Or any glass bottle that can keep out light. You can store it in the bottle one of two ways; Under a layer of water, or with a small ammount (0.5% by weight) of methanol added. I found that if you store it under water with methanol added, the methanol will act as an emulsifier to a small degree and dissolve some of your chloroform into the water. If you store the chloroform under water, you can use a rubber stopper to seal the bottle. If you store it with methanol added, you must use an organics proof cap or a ground glass stopper as the fumes will eat a regular stopper up. Remember, if you make dry chloroform, you have to store it with methanol, not under water. This seems obvious to most people, but some people will not think about this and pour water into their dry chloroform. Never ever sniff a bottle of chloroform. Even when its properly stored, it will slowly decompose into phosgene gas which is a deadly chemical warfar agent (but not near as deadly as hydrogen cyanide gas).

Disposal of leftovers

Chloroform is very poisonous to the environment and has been known to cause cancer in lab animals. The by-products of the reaction can be dumped down the drain (its only sodium acetate and sodium hydroxide) but the chloroform in the solution must be removed or destroyed somehow. The best method is to leave a bucketfull of the by-products sitting out in the sun for a day or so. The chloroform will evaporate off or decompose from the light. Warning: When chloroform decomposes, it forms phosgene gas, a deadly chemical warfar agent.